/// <summary>
/// Syncs the existing database data with new data loaded from the given directory
/// if an image exists in the directory but not in the database a new entry is created and if an image only exits in the database it will be deleted.
/// A progress notifier can be supplied as this function my take a long time to execute
/// </summary>
/// <param name="dir">directory to sync</param>
/// <param name="notifyProgress">Function that is periodically called to signify progress don by this method</param>
/// <returns></returns>
public async Task SyncPictureDataFromDirectory(string dir, Func <float, Task> notifyProgress)
{
Logger.Log(LogLevel.Information, "Requested file sync with files from directory [%s]", new { dir });
await notifyProgress(0.05f);
var paths = LoadPaths(dir);
await notifyProgress(0.2f);
var newPaths = await _picDb.FilterNewPaths(paths);
await notifyProgress(0.4f);
await _picDb.RemoveOldFromDb(paths);
await notifyProgress(0.6f);
await _picDb.InsertAll(newPaths.Select(LoadFromFile));
await notifyProgress(0.8f);
}